CPU: Either a CM 212+ for non-passive, or a Scythe Orochi for pure passive.
VGA: Either a TRad/Arctic-cooling twin turbo for non-passive, HR-03 series for pure passive (non-highend graphics though)
Fans: Nexus, Gelid, Arctic-cooling and Noctua all make super-silent fans.

CPU: Either a CM 212+ for non-passive, or a Scythe Orochi for pure passive.
VGA: Either a TRad/Arctic-cooling twin turbo for non-passive, HR-03 series for pure passive (non-highend graphics though)
Fans: Nexus, Gelid, Arctic-cooling and Noctua all make super-silent fans.

For cooling a completely passive videocard, it depends on airflow. That being said, I wouldn't go above a 4770/4850 passive Ati or GTS250/9800GTX+ passive Nvidia. With a fan though, even a low-rpm 92mm, you can go a good deal higher.

But you need at least an 120 mm exhaust fan and (optional) an 120 mm intake fan, both @7-800 RPM's.
Some time ago I've had an X2 3800+ with Ninja rev.B fanless and an 8800GT with AC S1 fanless but in my P182 I've had one exhaust and one middle intake @800 RPM's. No problems with temps or stability.